JPH10110246A - High strength steel wire for acsr, reduced in iron loss in high magnetic field - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve strength and corrosion resistance and to reduce iron loss by using low-carbon silicon steel of a specific composition and regulating conditions for plating after cold wiredrawing, afterdrawing, bluing, and warm stretching respectively. SOLUTION: A wire rod, having a composition consisting of, by weight ratio, 0.01-0.3% C, 0.6-6.5% Si, 0.10-1.5% Mn, and the balance essentially Fe and satisfying Si>=10×C+0.5, is used. It is preferable that one or more kinds among 0.002-0.05% Al and/or 0.002-0.10% Nb and 0.002-0.10% Ti are further added. Moreover, if necessary, minute amounts of Cu, Ni, Cr, Mo, Co, W, V, B, Rem, Ca, and Mg are added. At the time of manufacture of a steel wire, Zn or Al-Si- Zn alloy plating is performed and then wiredrawing is carried out at 20-80% reduction of area, and further, warm stretching is applied at 300-370 deg.C at a force 20-50% of the tensile strength of the steel wire. Further, the tensile strength of this steel wire exceeds 1500MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twisted steel wire (A) used to reinforce an Al conductor of a power transmission cable.
It is related to CSR (Aluminum Conductor Steel Reinforced).

[0002]

2. Description of the Related Art ACSR was devised by the US company ALCOA,
Because of the light weight of Al, it is often used as power transmission lines. However, since Al has low strength, it is used in combination with a steel wire plated with Zn or Al at the center of the ACSR for reinforcement.
Normally, JIS SWRH62 to 77A is used as a strand for the steel wire, and 3 to 19 steel wires after cold drawing are used. Such cores have strength, elongation, torsion,
Although there are regulations regarding breakage during the winding test, AC
There are no specific rules for iron loss when used as SR. However, in the actual steel core wire for ACSR,
Since current flows through the hard Al wire more closely aligned with the periphery of the steel stranded wire, there is a drawback that an induced current causes iron loss. Although this iron loss causes a large transmission loss, at present there is no means to prevent this iron loss.

[0003] In general, electrical steel sheets are used to reduce iron loss of transformers and motors, and grain-oriented electrical steel sheets having a uniform crystal orientation with respect to the rolling direction, and non-oriented electrical steel sheets having crystal orientations randomly arranged. It has been known. In these electromagnetic steel sheets, steel containing C is used in the manufacturing process in order to control the crystal orientation.
To 30 ppm or less. This method requires great manufacturing costs. In addition, all of them relate to a thin plate, and there is no report on a method of reducing iron loss when a stranded wire is twisted with a surrounding hard Al wire.

[0004]

The present invention relates to a steel core wire for an ACSR capable of reducing iron loss at the time of power transmission by specifying a component system and a manufacturing condition of a steel wire, and a method of manufacturing the same. .

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention makes it possible to reduce the power loss during power transmission by limiting the composition of the steel material and selecting the manufacturing conditions of the steel material. An object of the present invention is to provide a steel core wire for ACSR and a method for producing the same. That is, the summary is as follows.

(1) C: 0.01% to 0.1% by weight.
3%, Si: 0.6% to 6.5%, Mn: 0.10% to
1.5% and the relationship between C and Si is Si ≧ 10 × C +
0.5, with the balance being Fe and unavoidable impurities, high intensity A with low iron loss at high magnetic field.
Steel wire for CSR.

(2) Al: 0.002% by weight%
The high-strength steel wire for ACSR having a high magnetic field and a low iron loss according to (1), characterized by containing 0.050%. (3) By weight%, Nb: 0.002% to 0.10%, T
i: High strength with low iron loss in a high magnetic field according to any one of (1) to (2), wherein one or more of 0.002% to 0.10% is contained. Steel wire for ACSR.

(4) Cu: 0.02% to 0.5%, Ni: 0.02% to 0.5%, Cr: 0.02% to 0.5%, Mo: 0. (1) to (2) to 0.5%, Co: 0.02% to 0.5%, and W: 0.02% to 0.5%. (3) The high-strength steel wire for ACSR having a high magnetic field and a low iron loss according to any one of (3).

(5) V: 0.002% to 0.1% by weight.
High-strength ACS with low iron loss in a high magnetic field according to any one of (1) to (4), characterized by containing 10%.
Steel wire for R. (6) By weight%, B: 0.0002% to 0.0025%
The steel wire for high-strength ACSR having a high magnetic field and a low iron loss according to any one of (1) to (5), comprising:

(7) Rem: 0.002% by weight%
0.10%, Ca: 0.0003% to 0.0030%,
Mg: 0.0003 to 0.01% of one or more of the following: (1) to (6), a high magnetic field and a high strength ACSR having low iron loss and high iron loss. For steel wire.

(8) A steel wire is Zn-plated, or hot-dip-plated by using an alloy bath containing Zn and unavoidable impurities with Al: 2 to 12%, Si: 0.01 to 0.12% by weight. A high-strength ACS with low iron loss in a high magnetic field according to any one of (1) to (7),
Plated steel wire for R.

(9) The steel wire after plating has a total area reduction of 20 to 8
(8) The high-strength plated steel wire for ACSR according to (8), wherein the wire is drawn at 0% and the iron loss is low at a high magnetic field. (10) The plated steel wire for high-strength ACSR according to (9), wherein the drawn steel wire is subjected to a bluing treatment at a temperature of 300 ° C or more and 370 ° C or less.

(11) The drawn steel wire should be at least 300 degrees and 37
A high-strength ACSR having a high magnetic field and low iron loss according to (9), wherein the steel wire is heated at a temperature of 0 ° or less and a stress in a range of 20% to 50% of the tensile strength of the steel wire is applied during the heating. For plated steel wire. However, the high magnetic field here means that the magnetic field strength is 20
It means the case exceeding 00 A / m.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The technical idea underlying the present invention is as follows. Generally, iron loss can be separated into hysteresis loss and eddy current loss. The former is known to be affected by crystal orientation and steel purity. In the case of a steel plate, (11
0) It is desirable that [001] directions (so-called Goss directions) be integrated, and the higher the purity, the better. But,
Since a high-strength steel wire contains a large amount of C, the strength is increased. Therefore, when C is reduced, it is necessary to take a means of increasing the strength instead. Further, since wire drawing develops an intense fibrous texture, it is almost impossible to obtain a crystal orientation other than the texture unique to the drawn material. On the other hand, the latter eddy current loss decreases as the specific resistance increases,
Addition is known to be effective. In particular, in order to reduce iron loss in a high magnetic field (when the strength of the magnetic field is strong and exceeds 2000 A / m), high Si is effective. However, the high Si steel has low ductility and easily breaks when it is actually drawn. In order to solve such problems comprehensively, the present inventors have conducted various studies and found the following solutions.

In order to reduce the hysteresis loss, the C content must be reduced. Therefore, it is necessary to compensate for the decrease in strength due to the decrease in C by another method. In general, the higher the C content, the greater the increase in strength due to wire drawing.
If the amount is reduced, high strength by wire drawing cannot be expected much. However, by increasing Si instead of C, it is possible to increase the strength increase due to wire drawing. If Si is simply increased, the wire drawing workability is impaired and the wire is easily broken during wire drawing. However, by lowering the C content, the strength can be increased without impairing the wire drawing workability, and the hysteresis loss is reduced. Can also be reduced. In order to maintain good drawability, the contents of C and Si need to be within a predetermined range. Further, in order to reduce iron loss in a high magnetic field as intended by the present invention, it is necessary to add Si to C in a predetermined amount or more.

Hereinafter, the reasons for limiting the chemical components and the metal structure will be described in detail. First, the reasons for limiting the components of the present invention will be described. C is an effective element for strengthening the wire rod, but its content must be severely restricted in order to significantly increase iron loss. If it exceeds 0.3%, the increase in iron loss is remarkable, so the content is made 0.3% or less. on the other hand,
If it is less than 0.01%, it is impossible to obtain a strength exceeding 1500 MPa which is actually required, so the content range is set to 0.01% to 0.3%.

Si is effective as a deoxidizing element and increases the specific resistance to reduce eddy current loss. If the content is less than 0.6%, the effect is small. On the other hand, if it exceeds 6.5%, the drawability deteriorates, so the content range is set to 0.6% or more and 6.5% or less. In order to reduce iron loss in a high magnetic field exceeding 2000 A / m, Si needs to be in a range satisfying a predetermined relationship. Especially the Si content is C
It is necessary to add more than the amount satisfies a predetermined relationship. The authors conclude that the relationship between C and Si content is
Since it was found that iron loss in a high magnetic field was reduced when Si ≧ 10 × C + 0.5 was satisfied, C and S
The range of the content of i is set to the range of Si ≧ 10 × C + 0.5.

Mn is an element effective for toughening a metal.
If it is less than 0.10%, a sufficient effect cannot be obtained. On the other hand, if the content exceeds 1.5%, the toughness of the deposited metal deteriorates. Both Ti and Nb function effectively in terms of crystal grain refinement and precipitation hardening when added in very small amounts, but the effect is not obtained when the added amount is small, and an excessive amount increases the iron loss. In order to bring about Nb and Ti, the addition amounts of Nb and Ti are set to 0.002% to 0.10% for Ti and 0.002% for Nb.
% To the range of 0.10%.

[0019] Cu, Ni, Cr, Mo and W can all increase the strength of the steel. However, if the addition amount is small, the effect of increasing the strength by solid solution strengthening cannot be obtained. In order to deteriorate the ductility, the added amount is Cu: 0.02
% To 0.5%, Ni: 0.02% to 0.5%, Cr:
0.02% to 0.5%, Mo: 0.02% to 0.5%,
W: Limited to the range of 0.02% to 0.5%.

V is effective in increasing the strength of steel, but the effect is not obtained if the addition amount is small, and addition of an excessive amount causes an increase in iron loss. 0.002% to 0.10%. B is an element that improves the hardenability of steel. In the case of the present invention, the addition can increase the strength of the steel,
If the addition amount is small, the hardenability will not be improved, and excessive addition will increase the precipitation of B and impair ductility, so the content is made 0.0002% to 0.0025%.

Rem, Ca and Mg are effective in refining the metal structure by combining with S or oxygen. When a small amount is added, S remains as it is, and excessive addition causes an increase in iron loss, so Rem: 0.002% to 0.10
%, Ca: 0.0003% to 0.0030%, Mg:
It is added in the range of 0.0003% to 0.01%. Al is effective as a deoxidizing element. If the content is less than 0.002%, there is no effect, and if it exceeds 0.05%, surface flaws are likely to occur.
The range is 0%.

Next, the limiting conditions for the manufacturing conditions in the present invention will be described. The manufacturing process of the steel wire of the present invention does not need to be particularly defined. In other words, the ingot or slab cast and refined and cast in the normal steelmaking process is subjected to slab rolling as necessary starting from a steel ingot or a slab, and a steel wire is formed in the normal wire rod rolling process. The operating conditions in each process vary widely, and any of them is effective.

The steel wire usually used for the ACSR needs to be plated with Zn or an alloy such as Al—Zn in order to impart corrosion resistance. Corrosion resistance is improved by ordinary Zn plating, but when Al is added, better corrosion resistance is exhibited. Therefore, the amount of Al may be selected according to the severity of the use environment. However, if the Al content is less than 2%, the effect of improving the corrosion resistance is insufficient, and if it exceeds 12%, the plating temperature increases due to an increase in melting point, resulting in a decrease in steel wire strength. Therefore, the amount of Al in the plating bath is limited to 2% to 12% by weight. On the other hand, the reason why Si is added to the plating bath is to suppress the dissolution of Fe from steel facilities and equipment such as a plating bath and to suppress the generation of dross in the plating bath. If the added amount of Si is less than 0.01%, dross is generated, and if it exceeds 0.12%, Si does not dissolve in the plating bath, so the added amount is limited to 0.01% or more and less than 0.12%.

Usually, the strength is reduced by reducing the number of plating steps. Therefore, wire drawing (afterdrawing) is performed after plating to compensate for the strength. If the total area reduction rate is less than 20%, the strength is not sufficiently recovered, and if it exceeds 80%, the ductility is significantly deteriorated. Therefore, the range of the total area reduction rate is limited to 20% or more and less than 80%. Such wire drawing deteriorates the elongation of the product, so it is necessary to reheat to secure the elongation. If the heating temperature at that time is less than 300 ° C., the elongation is not sufficiently recovered, and if it exceeds 370 ° C., the plating layer is softened. Therefore, the heating temperature range is limited to 300 ° C. or more and less than 370 ° C. In order to further increase the strength reduced by plating, it is effective to apply a stress during heating. If the applied stress at that time is less than 10% of the tensile strength of the steel wire at room temperature, the strength increase is insufficient, and if it exceeds 50%, plastic deformation occurs locally and ductility is deteriorated. 10% to 50% of the tensile strength of steel wire at room temperature
Limited to the following.

[0025]

Next, the present invention will be described in detail based on embodiments. First, steel wires having the components shown in Table 1 were manufactured by refining (partially vacuum melting), continuous casting (partial steel ingot method and slab rolling), and wire rod rolling (hot rolling) by a normal converter method. Further, the strength was adjusted by drawing to a predetermined diameter by cold drawing. After cold drawing, some of them were subjected to plating, afterdrawing, bluing, and warm stretching under the conditions shown in Table 2. Table 2 shows the mechanical properties and the corrosion resistance magnification of these steel wires. Here, the corrosion resistance magnification was calculated by the following equation.

[0026]

Embedded image

[0027]

[Table 1]

[0028]

[Table 2]

Each of these steel wires was wound into a ring shape having a diameter of 270 mm, about 6 times, and further, 700 copper wires were wound on the primary side and 20 turns on the secondary side, and the iron loss was measured. For the measurement of iron loss, the relationship between the magnetic flux density and the magnetic field strength in alternating current was measured. The frequency was 50 Hz. Magnetic field strength (Hm) is 1
Iron loss was measured by changing the magnetic flux density (Bm) in the range of 2,000 to 4,000 (A / m) and 0.2 to 1.5 (T). Table 3 shows the measurement results of iron loss.

[0030]

[Table 3]

As shown in Table 3, the steel of the present invention has an extremely low C
Although it is steel, it has a tensile strength exceeding 1500 MPa. Furthermore, the elongation is relatively good, and it can sufficiently withstand the specification as the ACSR. By applying plating, corrosion resistance can be ensured. However, it can be seen that the corrosion resistance magnification is particularly large when Zn-Al plating is applied, and the effect is remarkable.

Further, as shown in Table 3, the steel of the present invention has a low iron loss in a high magnetic field region exceeding 2000 A / m. In particular, the iron loss tends to be lower as the C content is lower and the Si content is higher. You can see that there is. In addition, the relationship between the content of C and Si is
It can be seen that the comparative steels 8 and 9 not in the range satisfying ≧ 10 × C + 0.5 have high iron loss in a high magnetic field. When the heat treatment temperature after plating exceeds 400 ° C., the strength, elongation, and corrosion resistance magnification are all deteriorated. 6 applied stress during heat treatment
When it is as high as 0% σy, elongation is 12 and the corrosion resistance magnification is deteriorated. In addition, when the reduction in area after plating is excessively 81%, the elongation of 15 and 18 is deteriorated.

[0033]

As described above, the present invention has a high strength of 1500 MPa or more, is excellent in elongation and corrosion resistance, and has a lower iron loss in a much higher magnetic field than conventional steel. This makes it possible to greatly reduce the power loss when used as the core wire of the ACSR, and brings a great effect on energy saving.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Oba 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Kimitsu Works

Claims (11)

[Claims] 1. A weight percent of C: 0.01% to 0.3%, Si: 0.6% to 6.5%, Mn: 0.10% to 1.5%, and the content of C and Si A high-strength ACSR steel wire having a high magnetic field and a low iron loss, wherein the relationship is in the range of Si ≧ 10 × C + 0.5, and the balance is composed of Fe and inevitable impurities. 2. Al: 0.002% to 0.0% by weight.
The steel wire for an ACSR according to claim 1, wherein the steel wire has a high magnetic field and a low iron loss. 3. Nb: 0.002% to 0.1% by weight.
0%, Ti: one or two of 0.002% to 0.10%
The high intensity A having a low magnetic loss and a high magnetic field according to any one of claims 1 to 2, wherein the high intensity A contains at least one species.
Steel wire for CSR. 4. In% by weight, Cu: 0.02% to 0.5%, Ni: 0.02% to 0.5%, Cr: 0.02% to 0.5%, Mo: 0.02 % To 0.5%, Co: 0.02% to 0.5%, W: 0.02% to 0.5%. Item 4. A high-strength ACSR steel wire having a high magnetic field and a low iron loss according to any one of items 3. 5. V: 0.002% to 0.10% by weight
5. The high-strength ACS with low iron loss in a high magnetic field according to any one of claims 1 to 4, characterized in that:
Steel wire for R. 6. B: 0.0002% to 0.0% by weight
The high-strength ACSR steel wire according to any one of claims 1 to 5, wherein the steel wire has a high magnetic field and a low iron loss. 7. Rem: 0.002% to 0.10% by weight, Ca: 0.000% by weight
The high magnetic field according to any one of claims 1 to 6, comprising one or more of 3% to 0.0030% and Mg: 0.0003 to 0.01%. High strength ASR steel wire with low iron loss. 8. A steel wire is Zn-plated or hot-dip plated by using an alloy bath containing Zn and unavoidable impurities, with Al: 2 to 12% Si: 0.01 to 0.12% in weight ratio. The high intensity A having a low iron loss in a high magnetic field according to any one of claims 1 to 7, characterized in that:
Plated steel wire for CSR. 9. The steel wire after plating has a total area reduction rate of 20 to 80%.
The high-strength plated steel wire for ACSR according to claim 8, wherein the wire is drawn by a high magnetic field and a low iron loss. 10. The high-strength plated steel for ACSR according to claim 9, wherein the drawn steel wire is subjected to a bluing treatment at a temperature of 300 ° C. or more and 370 ° C. or less. line. 11. The drawn steel wire is heated at a temperature of 300 ° C. to 370 ° C. and the tensile strength of the steel wire during heating is 20 ° C.
The high-strength plated steel wire for ACSR according to claim 9, wherein a stress in a range of 50% to 50% is applied.